Abrasive sleeve holder



Patented Apr. 10, 1951 ABRASIVE SLEEVE HOLDER George A. Larson, Rockford, Ill.

Original application May 15, 1946, Serial No.

669,869, now Patent No. 2,483,422, dated October 4, 1949. Divided and this application Au- .gust 2, 1949, Serial No. 108,093

17 Claims.

This invention relates to a rotatable holder whereon may be fitted an abrasive sleeve in the form of a flexible endless band. In particular, the present improvements are concerned with the holder itself which comprises a rotatable hub from which are extended a plurality of resilient arms which at their Outer ends, either directly or through the medium of a peripheral band, support a surrounding abrasive sleeve. A feature of importance to this invention is the sleeve support which is yieldable so that, in response to a centrifugal force, it will tend to move out thereby pressing itself tightly against the surrounding sleeve. Conversely, when motionless, the support Contracts to a state of relaxation, the abrasive sleeve being then readily movable on or off the holder.

Certain embodiments of this invention are set forth in the accompanying drawng in the manner following:

Figure 1 is a view in side elevation of a onepiece expansible holder fitted with a surrounding abrasive sleeve, shown as it appears when motionless;

Fig. 2 is a similar view of a one-piece expansible holder of modifiedconstruction; and

Fig. 3 shows in side elevation a still different form of holder having a hub, armsand band formed of inter-connected pieces.

i The present-holderiin the form of Fig. 1 comprises a central hub 59 from which is extended a plurality of resilient arms 5`l each having at its Outer end an arcuate portion 52 which is concentric with the axis of the hub. These several arcuate end portions collectvely constitute a peripheral band for the holder. Through the center of the hub a bushing Or shaft B may be embedded to adapt the holder for attachment to a shaft or chuck whereby rotary motionV is transmitted thereto. An abrasive sleeve S which is placed around the holder is supported and driven thereby when the holderis in Operation.

In the construction of Fig. 1, the hub, arms, and band are shown as formed integrally of'one piece of resilient material, such as rubber. The arms which are extended radially Outwardly from the hub are integrally joined to the arcuate end portions 52 which terminate at their free ends in inwardly extending flanges 53, each disposed adjacent the next adjacent arm.

When at rest, the holder will be relaxed, i. e. it will be neither contracted nor expanded, its diameter then being such that the abrasive sleeve S may be easily slipped on or Oif by twiste ing the sleeve in the direction in which the arms scope with one another is prevented by the flanges extend. When a rotary force is applied to its hub, the arms will be pulled around to transmit this force to'the peripheral band which tends to expand with increase in the centrifugal force that is developed, the arms offering little or no resistance to this expanding movement of the band. Since the abrasive sleeve is relatively nonstretchable, the expanded band will press closely and tightly against the inner face'of the sleeve at every pointwhereby to establish a secure driving connection therewith. The sleeve may accordingly be depended upon to rotate with the holder without slipping.

When pressed against a piece of work, the peripheral band will tend to flatten at the point where engagement takes place. There is accordingly a potential substantial area of contact between the abrasive sleeve and the work, instead of merely a line contact as in cases where the holder is incapable of yielding.

The arcuately curved portions 52 form a nearly uniform peripheral layer or sectional band so that the centrifugalforce is substantially uniform at all points. Although the arcuately curved portions 52 Of the arms come quite close to one another, any danger that they will tele- 53. The slight spacing between the arms, or between the free end of one arm and the radial portion of the next arm, permits a very easy reduction in size of the holder below its natural size when twisting the sleeve onto the holder by rotating the sleevein the direction'that the arms extend. Thisis desirable because it facilitates applying the sleeve' even though the holder is large enough in its relaxed size to hold the sleeve quite reliably.

In Fig. 2 the holder comprises a hub formed i with an axial Opening 60, and provided with integral arms GI having arcuately curved portions 62 terminating in relatively heavy end portions 63. The arms are separated by slots 64 Opening into apertures 65. The sleeve will be gripped with an enhanced force due to the relatively heavy masses 63 at the free ends of the arms.

In Fig. 3 a form of the invention is shown which is particularly appropriate for larger sizes of sleeves S. In this form is a hub 10 in whose axial Opening may be received a bushing or shaft B. The hub is provided with keyhole slots- 'H into which oppositely bowed arms 12 are fitted, each branch of the arm being integral with a curved portion 13 concentric with the axis Of the hub 10. The form of arms in this construction is perhaps the most uniformly flexible of all, but

involves a more complicated mold structure and also requires an assembly Operation with the hub. The hub may be formed of plastic, wood, metal, or other material.

In Figs. 1 and 2 the holder may be molded as one piece of rubber to a metallic shaft or spindle which may be knurled or ribbed. It should be observed that these constructions are exceedingly simple to manufacture since the holders may be formed to the final shape with relatively simple molds.

All of the forms of the invention may be `.driven in either direction. Ordinarily, it will be preferred to drive the holders in the direction in which the arms extend from the more radial portions thereof. With this direction of rotation the drag on the sleeve resulting from the abrasive use thereof will tend to flex the arms in such a manner as to increase the force they exert against the sleeve. rotation in the opposite direction may be preferred.

It is important to have at least three and preferably four or more arms. With only two arms, very little pressure is required to push the sleeve off center with respect to the axis of the hub.

A salient characteristic of the present holder is its capacity to expand evenly under rotation so as to bear with pressure against ,,the surrounding sleeve. A condition of expansion is normally attained when the holder is in Operation, and a Condition of relaxation when the holder is still. This makes for security in the connection between the abrasive sleeve and the holder when the device is operated, and for ease in removal of the sleeve and replacement of a substitute sleeve, whenever desired. In addition, the expanded peripheral band of the holder is susceptible of yielding when the sleeve is pressed against the work, so as to enlarge the area of its surface contact therewith. Accordingly, in many cases the time required for performing a given task may be materially reduced or the quality improved.

Successful performance of the present sleeve holder is also attributable to another factor, viz. the form and arrangement of the arms which transmit the rotary force to the surroundng sleeve. These arms, while resilient, are stiff or self-sustaining enough to move the band through between each arm and the band, when a band is f' provided, is confined to a relatively small area at the arm extremity, leaving the arms and band elsewhere in freely separable relation. This is important in facilitating a uniform and even expansion or outward movement of the band at every point in its periphery when rotation takes place. The band is .accordingly free to expand at every peripheral point, even at'the arm extremities where connection is made with the band. In every case the holder furnishes a rotatable, fioating, yieldable, driving and concentr1c support for the abrasive sleeve such that it may be easily slipped on and off when motionless, and be fiattened somewhat at the point of Its engagement With the work Whereby to enlarge its area of contact therewith.

It will be observed that in both of Figs. 1 and 2 the arcuate portions of the arms each terminate at its free end in a portion too thick to pass between the adjacent arm and the ,sleeve rand DOS- When a very soft action is desired,

between the adjacent arm and the sleeve.

sibly be gripped between them. It is preferred to have a thickness of about a quarter of the radius of the holder, this thickness in the case of Fig. 1 including the flange 53. It is believed, however, that anything over one-eighth of the radius of the holder would be sufcient. In fact, the fiange 53 in Fig. 1 may be omitted entirely with only slight danger of occasional inconvenience due to the gripping of an arcuate portion In all of the forms of the invention the arcuate portions may be impregnated with an abrasive so as to make the addition of an abrasive sleeve unnecessary. However, this abrasive sleeve is preferred since it controls the working dimensions and is inexpensive to replace.

In Fig. 2, the apertures 65 may be omitted, but each slot 64 should desirably extend close to the adjacent slot so that as in the illustrated forms the arcuate portions of the arms Will be connected to the hub only by a portion of relatively small cross-section. Particularly, it is desirable that in all forms there be one point between the arcuate portion of the arm and the hub where the connecting material is small in the circumferential direction in keeping With the dimensions marked a in Fig. 2. This, together with the free-ended arms, provides a high degree of fiexibility and expansibility.

The dimension a in Fig. 2 may be increased considerably beyond that shown although some of the advantages of the invention may thereby be lost unless high flexibility of the arms is provided in some other Way. At the present time it is preferred that the dimension a be approximatelyas shown, namely, in the order of l of the radius of the holder. One alternative way of providing flexibility of at least the terminal portion of the arm is to move the aperture 6-5 closer to the circumference as the dimension a is increased. 1

The holder may, of course, be made of synthetic rubber, such as the Buna rubbers, including Buna S, and Neoprene as well as compounds of natural rubber. Any such materials may be deemed to be included in the term rubber-like used in the claims, provided that they are fiexible, compressible, elastic, andstable at slightly elevated Operating temperatures, thus resembling ordinary soft vulcanized rubber.

This application is a division of my application Ser. No. 669,869, filed May 15, 1946, now Patent No. 2,483,422, dated October 4, 1949.

1. The combination with an abrasive sleeve of an internal holder therefor of molded rubber-like material forming an expansible support-for the abrasive sleeve and initially having a diameter greater than that of the sleeve interior, the holder comprising a rotary expanding member including a hub and a plurality of i'lexible arms carried thereby, extending outwardly from the hub and having portions extending concentrically with the sleeve and spaced from the hub,'the concentrically arranged portions of said arms being separated by a narrow gap and free for independent movement in a radial direction.

2. A rotary expanding holder including a hub and a plurality of fiexible arms molded integrally therewith of rubber-like material extending outwardly from the hub and independently fiexible with respect thereto, and having portions extending concentrically with and spaced from the hub with arcuate surfaces forming a circular peripheral support Whose diameter is initially slightly greater than that of a sleeve suitable for fitting on to the holder, said peripheral support consisting of separate sections separated at their ends by a narrow gap and exp-ansible in a radial direction independently of one another.

3. A rotary expanding holder including a hub and a plurality of flexible arms molded integrally therewith of rubber-like material extending outwardly from the hub and independently fiexible With respect thereto, and having portions extending concentrically With and spaced from the hub to provide an arcuately sectional band forming a circular support for an abrasive sleeve and having initially adiameter slightly greater than that of the sleeve, the sections of said band being separated at their ends from one another by a narrow gap and expansible in a radial direction -independently of one another, said arms being resilient whereby the abrasive sleeve will be held thereon, When stationary, by friction resulting from resilient pressure of the arms toward the band, said pressure being aug'mented by centrifugal force during rotation of the holder.

4. The combination of an abrasive sleeve and an internal holder therefor comprising a rotary expanding member including a hub and a plurality of fiexible arms molded integrally therewith of rubber-like material, extending outwardly from the hub, independently flexible with respect thereto, and having portions extending concentrically With and spaced from the hub, said concentrically extending portions presenting outer arcuate surfaces forming a circular peripheral support for an abrasive sleeveV and having initially a diameter slightly greater than that of the sleeve, the circular peripheral support consisting of separate sections spaced at their ends from one another by a narrow gap and expansible in a radial direction independently of one another.

5. The combination of an abrasive sleeve and an internal holder therefor of molded rubber-like material comprising a rotary expanding member, including a hub, soft, fiexible, resilient arms disposed outwardly thereof and secured to the hub by means integral with the arms, the outer ends of the arms being free for movement in a radial direction, each arm having an arcuate surface extending concentrically with the hub approximately all of the way between tWo adjacent arms forming a circular supporting surface for the abrasive sleeve, said circular supporting surface consisting of separate sections spaced at their ends from one another by a narrow gap and expansible in a radial direction independently of one another.

6. The combination of an abrasive sleeve and an internal holder therefor comprising a rotary expanding member including a hub, soft, flexible, resilient, pressure-exerting means disposed out- -wardly of the hub, molded integrally thereWith of rubber-like material, and connected therewith at a plurality of points spaced around the hub and having outer pressure surface portions provided With arcuate peripheral surfaces extending approximately throughout the periphery of the member forming a circular support for the abrasive sleeve, said circular support consisting of separate sections spaced at theirl ends from one another by a narrow gap and expansible in a radial direction independently of one another.

7. A rotary expanding abrasive sleeve holder including a hub, and a plurality of arms of rubber-like material extending radially from the hub and providing outer arcuate surfaces arranged concentrically withothe hub and forming a circular peripheral support forthe abrasive sleeve, said circular peripheral support consisting of ,separate sections separated from one another by a slight gap and expansible in a radial direction independently of one another, said holder being initially of slightly greater diameter than that of the abrasive sleeve.

8. A rotary expanding member including a hub, and a plurality of fiexible arms molded integrally therewith of resilient rubber-like material and extending outwardly from the hub and independently flexible with respect thereto and having outer portions extending concentrically with and spaced from the hub and forming a circular peripheral support for an abrasive sleeve, said circular peripheral support consisting of separate sections separated from one another by a` narrow gap and movable inwardly in a radial direction with respect to the sleeve and away ,from the same to compensate for relative rotary movement of the hub and the sleeve.

9. The combination of an abrasive sleeve and a rotary expanding support member therewithin formed integrally of rubber-like material, in-

cluding a hub surrounding the axis of the member, and a plurality of radial extensions carried thereby, each extension including a portion having an outer arcuate surface extending circumferentially approximately the entire distance besive sleeve, said circular support consisting of separate sections separated from one another at their ends by a narrow gap and expansible in a radial direction independently of one another, and a portion of relatively small thicklness in the circumferential direction connecting said circumferential portion with the hub.

10. The combination of an abrasive sleeve and a rotary expanding support member therewithin formed integrally of rubber, including a hub surrounding the axis of the member, and a plurality of extensions extending generally radially out from the hub at their junction therewith, each extension including a portion having its outer surface extending circumferentially and extending approximately the entire distance between the outer surfaces of the adjacent extensions and each portion being separated from those adjacent by a narrow gap and expansible in a radial direction independently of the others, and a portion of relatively small thickness in the circumferential direction connecting said circumferential portion With the hub.

11.l A rotary expanding abrasive sleeve holder including a hub and a plurality of driving means of rubber-like material extending away from the hub in a plane transversely of its axis and comprising outer arcuate sections arranged concentrically with the hub and forming a sectional band for support thereon of the abrasive sleeve, and each section separated from those adjacent by a narrow gap and expansible in a radial direction independently of the others, each of said arcuate sections being inwardly extended at one free end portion thereof to increase its weight Whereby to engage the surrounding abrasive sleeve with greater force at that point in response to centrifugal pressure.

12. An abrasive sleeve holder comprising a rotatable hub, a resilient arcuately sectional band for supporting a surrounding abrasive sleeve, the band being concentric with the hub and expansible under centrifugal force for movement outwardly away from the hub, said sections of the band being separated from those adjacent by a narrow gap and expansible in a radial direction independently of the others, and resilient driving means formed integral with the band and removably interlocked with the hub.

13. An abrasive sleeve holder comprising a hub, a band made up of arcuate sections for supporting a surrounding abrasive sleeve, the band sections being arranged concentrically with the hub and expansible independently under centrifugal force for movement outwardly away from the hub, and resilient driving means interconnecting the band with the hub comprising a pair of arms joined integrally with each band section near opposite ends thereof.

14. An abrasive sleeve holder according to claim 13 wherein each pair of arms is removably interlocked with the hub.

15. An abrasive sleeve holder according to claim 13 wherein the arms of each pair are oppositely bowed.

16. An abrasive sleeve holder according to 8 claim 13 Wherein the arms of each pair are bowed outwardly and away from each other.

17. An abrasive sleeve holder comprising .a rotatable hub, a resilient arcuately sectional band for supporting a surrounding abrasive sleeve, the band being concentric with the hub and expansible under centrifugal force for movement outwardly away from the hub and the sections of the band being separated from one another at their ends by a narrow gap and expansible in a radial direction independently of one another, and resilient driving means formed integral with the band and connected with the hub.

GEORGE A. LARSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 540,828 Casgrain June 11, 1895 2,377,880 Gutsell June 12, 1945 

